7 Cylinder amp for the new chassis - Is this layout "politically" correct ?

[kagliostro]

I'm not asking to revise the layout, but I would like to know if it seems correct as general distribution of the path

this is the schematic



Here the original project with photos

http://www.bensykora.com/7cylinder.html

and this is the layout I've draw



Thanks

Franco

[PRR]

Volume pot is very close to output transformer and power tube plates.

"7 cylinder" caught my eye. For an instant I said "there are no 7 cylinder engines", then DUH!! I remember all those Radial engines.
http://en.wikipedia.org/wiki/Fiat_A.54
http://en.wikipedia.org/wiki/Fiat_A.50
http://en.wikipedia.org/wiki/Jacobs_R-755

I had no idea that Isotta Fraschini was still in business. Used to be exotic race cars and stuff. Now a lot of very large Diesel engines, to 67 Liters. Anyway they once made a very large 7-jug radial, but I can not find a picture.

[kagliostro]

Ciao PRR

The layout for tubes and transformers will be the same as in Doug's Stout



---

A pair of month ago I met a guy who lives not far from my town, he is member of a CNC forum where also I'm member, he is an HiFi passionate

and in the past has had its own HiFi brand and a model of guitar amp in production

he also had a brand who builded this kind of stuff, the activity had problems (here in Italy at the moment isn't impossible to be without) and stopped the production

but now he is newly starting the activity

give a look here

http://www.slengines.com/constellation_en.html

at his house I've seen other very nice stellar motors

Those small stellar engines are really cool

Thanks for the answer

Franco

[HotBluePlates]

It would be a good idea to draw your layout using part symbols which are to-scale, or where the relative sizes are accurate. That will give you a better idea of how long wire runs will be and if wires will cross sensitive areas.

Also, a 100nF cap if very likely not the same size as a 1/2w resistor. You may find your turret board may not want exactly equal spacing, depending on which specific parts you use.

Microsoft Visio is probably too expensive to buy for one-off projects, but I used it to produce the layout of my last amp because every part can be drawn to scale. I knew exactly how everything would fit in advance, and where every wire would run. The amp went together with no surprises (which was a nice change  ).

[kagliostro]

Ahem .... err .... I've Visio, not the latest version, but I've , only I'm not very confident with it, I know, I must study more  .....

I've redraw the layout trying to respect a scale

the measures of the top of the chassis are 300mm x 180mm, front and rear panel are 300mm x 60mm

Turet spacing is based on a grid of 10mm, so components are placed on parallel columns that are 10mm distant each other

there are 22 colums (virtually 23) of components in a grid of (virtually) 9 rows distant 10mm each other

As I'm not able to do better, PT and OT as they are on the top of the chassis are draw on one other parallel place as they will be on the

top of other components, they are exactly placed in relation to the other components



Is the ground scheme I've draw correct in relation to Doug's grounding recommendations ?

Thanks

Franco

[printer2]

Looking at the schematic I am wondering about the phase inverter, are the 330k resistors right?

[kagliostro]

I hope .... the PI isn't the usual PI it is a Floating Paraphase, if I'm not wrong

http://www.valvewizard.co.uk/floatingparaphase.html

K

[DummyLoad]

missing feedback resistor - 33K


--pete

[kagliostro]

Ciao Pete

missing feedback resistor - 33K

Err... which 33k resistor 

I don't see one on the schematic, where is it connected ? 

Franco

[DummyLoad]

Look closely at merlin's schematic. Follow the 1m and 33k. Your amp has 2x330k instead of 2x1m and 33k.

--pete

[kagliostro]

I see ....

Might be that worths to give a try to that feedback resistor

The autor say the PI is inspired to '60 Supro and Valco design, but I wasn't able to find an exact copy of his solution among those schematics

Franco

[PRR]

> Visio,... I'm not very confident with it

I like graph paper. On 1/10th-inch grid a resistor is (maybe) 2 by 6 squares, a 0.47u 600V is (maybe) 5 by 12 squares, etc. I think I can mark-up a grid faster than I can select and drop parts on a computer.

Graph paper is getting harder to find, true. I have two sources for basic 0.1" grid within 15 miles, but if not (or if you need something special), there are on-line graph paper tools which output a PDF you can print when needed.
___________________

_I_ think PT CT should go DIRECT to first filter cap "_", -then- on to common ground.

[kagliostro]

PRR

I'll try to get info about graph paper

EDIT: Oh, I see, I've understand what you mean, here we call it Carta Millimetrata, and in the past (years ago) I used it often 

Franco

[kagliostro]

Thanks for the suggestion

but, as told, I've Visio and it will be better I study more his usage


At the moment I've draw a new layout that is in scale with the chassis dimensions (assuming a chassis of 300mm x 180mm x 60mm)





K

[kagliostro]

Whell, I followed the council about to use a program that can give real size correspondence and the board become larger of ~4cm




this id my first Visio layout and if you have councils I'm here to listen for it

Here the .vsd Visio file

http://www.mediafire.com/download/16kev1wb7o096u3/7_Cylinder_Layout_Assiali.rar


Thanks


Franco


p.s.: Thanks to Pete & Steve for the 7 pin socket for Visio as I was missing it

[sluckey]

That looks much, much better than my first layout. 

[kagliostro]

Thanks Steve, isn't me, it's Visio

I was wondering if PI ground is to be connected with the preamp ground or with PA ground ? 

Franco

[sluckey]

I was wondering if PI ground is to be connected with the preamp ground or with PA ground ?

The 220K grid resistors need to connect to the power amp ground. Since you already have those resistors connected to the negative end of the PI filter cap, just connect the PI cathode R/C to that same turret and put a jumper over to the onboard power amp ground buss. See pic...

[kagliostro]

Molte Grazie Steve



Franco

[DummyLoad]

very nice work franco. 


--pete

[kagliostro]

Thanks Pete

but I have no merit, is visio that does everything

Franco

[sluckey]

Thanks Pete

but I have no merit, is visio that does everything

Franco

Ha! All those nice shapes were made by smart people just like you. 

[kagliostro]

You are right Steve, without those shapes .... Visio is really nothing

Many Many thanks to all the friends that has contributed to the creation of that indispensable database

Franco

[rafe]

thanks

[PRR]

Of course 7 cylinder radials are very common.
"By 1933, Jacobs had developed its most famous engine, the L-4 seven-cylinder air-cooled radial, with a power rating of 225 hp (168 kW) displacement of 757.7 cu in (12,416 cc). It was better known as by its military designation, R-755.
Due to the tendency of the L-4 engine to vibrate heavily at low rpm, it was given the nicknames Shakin' Jake and Shakey Jake."

In-line Sevens:

2 minute video of 7 cylinders

more

[bmccowan]

I ride a Moto Guzzi V7. Not 7 cylinders - a V-twin. But the design of the original Guzzi V-twin was based on a radial aircraft engine. Viva Italia!

[thetragichero]

maybe a small nit to pick but the power earth ground should be attached to its own bolt on the chassis instead of sharing a bolt with other grounds (this illustration could just be showing star grounding or whatever but i figure it's best to wire an amp as safely as possible